Air squeezing core machine



Oct. 18, 1966 E. MATHYS AIR SQUEBZING CORE MACHINE Filed Oct. 26, 1964 INVENTOR United States Patent 3,278,996 AIR SQUEEZING CORE MACHINE Ernst Mathys, Schalfhausen, Switzerland, asslgnor to Georg Fischer Aktiengesellschaft, Schaiihausen, Switz- The present invention relates to an air squeezing core machine, and, in particular, is directed to the supply of compressed air into the sand container of the machine.

As is well known, a core squeezing or shooting machine consists primarily of a compressed air container and a sand container the lower part of which leads into the socalled squeezing head. The core squeezing machine furthermore comprises a shut-off valve and a squeezing valve between the compressed air container and the sand container.

The operation of the core shooting machine has a fundamental difiiculty inherent thereto which consists in that the sand mass engages the inner wall of the sand container at a high friction and has a considerable tendency to adhere to the inner wall of the sand container. This greatly enhances the danger that, depending on the design of the sand container (ratio of diameter to length) and of the squeezing head (arrangement of the blowing nozzles or slots) corresponding holes are squeezed out of the sand mass.

Devices have been suggested for overcoming this drawback. More specifically, it has been suggested to -over-' come these drawbacks by means of an agitator in the sand container and by means of a bore or slot insert whereby between such insert and the inner wall of the sand container an annular chamber is produced which is subjected to compressed air prior to or simultaneously with the initiation of the squeezing operation, whereby the sand column detaches itself from the insert, with the result that the sliding movement of the sand mass is improved.

It is an object of the present invention to provide a core squeezing machine of the above-mentioned general type which, however, will not require an agitator in the sand container and/ or a bore or slot insert.

It is another object of this invention to provide a core squeezing machine as set forth in the preceding paragraph which will bring about a proper detachment of the sand column from the inner wall of the sand container.

It is still another object of this invention to provide a core squeezing machine as set forth above, which will result in an improved exploitation of the expansion energy of the compressed air so that the consumption of compressed air will be reduced and, accordingly, also the energy consumption.

Still another object of this invention consists in the provision of a core squeezing machine as set forth in the preceding paragraphs, which over heretofore known core squeezing machines will be considerably simplified in construction and, therefore, will greatly reduce production costs.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing showing a diagrammatic illustration of an embodiment of the present invention.

As is well known, when core shooting, the sand mass is, by means of expansion energy of compressed air, conveyed from the sand container to the core box and compacted. In this connection, everything should be avoided that may result in an uneconomic consumption of com- "ice pressed air and in energy losses caused by long feeding lines, bends in the line, and changes in cross-section which have an unfavorable effect in flow technical respect.

The problem underlying the present invention has been solved by providing a nozzle between the pressure chamber and the sand container and by so designing the nozzle that the opening thereof in the same manner as a Laval nozzle first conically decreases in diameter and, while extending into the sand container, conically increases in diameter again. In addition thereto, the present invention is characterized in that the squeezing valve, the pressure chamber, the Laval nozzle, the sand container, and the squeezing head have their axes in alignment with each other.

Referring now to the drawing in detail, the core shooting or core squeezing machine shown therein comprises a sand container 1 which is so designed that it conically increases in diameter in the direction from the upper portion to the lower portion thereof. The said sand container at the same time forms a part of a Laval nozzle 2.

The sand container 1 is composed of two sections, viz. the upper section and alower section. The upper section is designed as Laval nozzle and leads into the pressure chamber 5. The said upper section of sand container 1 serves to convert pressure energy into speed energy and also creates a non-turbulent air flow. The lower section of the sand container which represents the sand container proper forms the extension of the diffuser of Laval nozzle 2. The lower end of sand container 1 is in a manner known per se followed by the squeezing head 3 with blow nozzle 9.

At the upper end of the sand container, adjacent Laval nozzle 2, there is provided the above-mentioned pressure chamber 5 which in turn forms a part of the compressed air container or reservoir 6. As squeezing valve or shutoff valve, which is controlled by a control valve 16, there is provided a double-acting cylinder-piston system with a cylinder 4 and a piston 11, which latter is provided with a sealing disc 13 and closes ofl? pressure chamber 4 with regard to the upper opening of nozzle 2. When a flap 7 provided in the top section on one side in said sand container 1 is in open position, sand is automatically conveyed from a sand storage container 12 through an opening 7a into sand container 1 by means of a rotary feeding plate 8, driven by a motor 14. The flap 7 is opened or closed by means of an air motor 15. Pressure chamber 5 which forms a part of the compressed air container 6, the squeezing valve 4, 11, nozzle 2, and sand container 1 with squeezing head 3, as well as the core box 10 are so arranged that their axes are in alignment with each other whereby the compressed air can expand in one squeezing direction only.

The above arrangement of Laval nozzle 2 on sand container 1, and the design of said nozzle 2 brings about that on one hand the sand column is uniformly subjected to air pressure over the entire cross-section of sand container 1, while on the other hand the sand column is reliably detached from the inner wall of sand container 1 under practically complete elimination of friction between the sand column and the sand container wall engaged thereby. The friction-free detachment of the sand column from the sand container 1 takes place already during the first phase of the squeezing operation, inasmuch as an annular air chamber forms between the cone of sand container 1 and the cone of the sand column. As a result thereof, all devices such as, for instance, a slot insert with long feeding lines, and an agitator, etc., as required with heretofore known core squeezing machines have become entirely superfluous.

It is, of course, to be understood that the present invention is, by no means, limited to the particular construction shown in the drawing, but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. A core shooting machine, especially for foundry sand, which includes: first chamber means adapted to receive and store air under pressure, second chamber means adapted to be charged with sand from which a core is to be shot, nozzle means interposed between said first and second chamber means and communicating therewith, said nozzle means having a restriction near said first chamber means and also having a first flaring section flaring from said restriction toward said first chamber means, said nozzle means furthermore having a second flaring section flaring from said restriction in the direction toward said second chamber means, said first flaring section 'being relatively short with regard to said second flaring section, a funnel-shaped shooting head having its interior in communication with the interior of said second chamber means while having its wide end adjacent said second chamber means and having its narrow end provided with a discharge mouth, and shooting means including means extending into said first chamber means and operable to squeeze air under pressure from said first chamber means into said secondchamber means to thereby shoot sand from said second chamber means through said discharge mouth into a core box, said shooting means and said second chamber means as well as said funnel-shaped shooting head being in substantially axial alignment with each other.

2. A core shooting machine according to claim 1, in which said second flaring section merges with said second chamber means.

3. A core shooting machine, especially for foundry sand, which includes first chamber means adapted to receive and store air under pressure, nozzle means arranged adjacent to and communicating with said first chamber means, said nozzle means having a restriction near said first chamber means and also having a first flaring section flaring from said restriction toward said first chamber means, said nozzle means furthermore having a second flaring section flaring from said restriction in a direction away from said first flaring section and having one portion thereof forming second chamber means for receiving sand from which cores are to be shot, said first flaring section being relatively short with regard to said second flaring second, a funnel-shaped shooting head having its interior in communication with the interior of said second chamber means while having its wide end adjacent said second chamber means and having its narrow end provided with a mouth, and shooting means including means extending into said first chamber means and operable to squeeze air under pressure from said first chamber means into said second chamber means to thereby shoot sand from said second chamber means through said mouth into a core box, said shooting means and said second chamber means as well as said funnel-shaped shooting head being in substantially axial alignment with each other.

4. A core shooting machine according to claim 1, in which said first chamber means includes a compressed air storage tank and an auxiliary chamber communicating with said tank and located in the path of said shooting means.

5. A core shooting machine according to claim 1, in.

which said'shooting means comprises a fluid operable cylinder piston system.

References Cited by the Examiner J. SPENCER OVERHOLSER, Primary Examiner.

E. MAR, Assistant Examiner. 

1. A CORE SHOOTING MACHINE, ESPECIALLY FOR FOUNDRY SAND, WHICH INCLUDES: FIRST CHAMBER MEANS ADAPTED TO RECEIVE AND STORE AIR UNDER PRESSURE, SECOND CHAMBER MEANS ADAPTED TO BE CHANGED WITH SAID FROM WHICH CORE IS TO BE SHOT, NOZZLE MEANS INTERPOSED BETWEEN SAID FIRST AND SECOND CHAMBER MEANS AND COMMUNICATING THEREWITH, SAID NOZZLE MEANS HAVING A RESTRICTION NEAR NEAR SAID FIRST CHAMBER MEANS AND ALSO HAVING A FIRST FLARING SECTION FLARING FROM SAID RESTRICTION TOWARD SAID FIRST CHAMBER MEANS, SAID NOZZLE MEANS FURTHERMORE HAVING A SECOND FLARING SECTION FLARING FROM SAID RESTRICTION NEAR SAID FIRST CHAMBER SECOND CHAMBER MEANS, SAID FIRST FLARING SECTION BEING RELATIVELY SHORT WITH REGARD TO SAID SECOND FLARING S ECTION. OF FUNNEL-SHAPED SHOOTING HEAD HAVING ITS INTERIOR IN COMMUNICATION WITH THE INTERIOR OF SAI SECOND CHAMBER MEANS WHILE HAVING ITS WIDE END ADJACENT SAID SECOND CHAMBER MEANS AND HAVING ITS NARROW END PROVIDED WITH A DISCHARGE MOUTH, AND SHOOTING MEANS INCLUDING MEANS EXTENDING INTO SAID FIRST CHAMBER MEANS AND OPERABLE TO SQUEEZE AIR UNDER PRESSURE FROM SAID FIRST CHAMBER MEANS INTO SAID SECOND CHAMBER MEANS TO THEREBY SHOOT SAND 